It is well-known for the front hood of motor vehicles to be assigned a closure system which, besides its locking and release function, additionally ensures that upon release of the front hood, it initially can only be opened in limited fashion, so as to be able to be folded up into its end position only after being released by a safety catch hook.
Thus, for example, German Patent No. 42 39 908 describes a rotary-latch closure, particularly for locking the engine hood of motor vehicles, that is based on a retaining pawl, as well as a rotary latch operatively connected to the U-shaped striker. In the case of this rotary-latch closure, in the locked position of the engine hood, a u-shaped fork opening of the swivel-mounted rotary latch receives the middle limb of the striker in such a way that it is retained, and thus the engine hood is locked. If the intention is to release the engine hood, it is initiated by actuation of a retaining pawl, likewise swivel-mounted, by way of a cable pull, by release of an arresting action by stops assigned to the retaining pawl and the rotary latch. Starting out from the assumption that the rotary latch is under the force of an elastic spring element, the swivel motion resulting therefrom takes along the striker via its middle limb vertically upward until finally it is blocked in its vertical displacement in the end position of the rotary latch by a safety hook fixedly joined to a closure housing. During the vertical displacement of the striker and therefore of the middle limb, it is guided within a sliding channel, the inside width of the passage cross-section being completely covered by the hook end of the fixedly disposed safety hook. At the level of the catching limb of the u-shaped fork opening, the sliding channel, upon reaching the end position of the rotary latch, passes over into a centering shaft in such a way that the cross-section of the sliding channel is enlarged in wedge-shaped fashion in the upper closure area. In the case of this rotary-latch closure, in order to permit a complete opening of the engine hood after the striker has been blocked via its middle limb by the safety hook, the striker is joined to a lever plate which is swivel-mounted in a bearing plate. In this context, the side limbs of the striker are screw-fitted to the bottom side of the lever plate.
However, achieving the swiveling motion of the lever plate, which is necessary in order to swivel the middle limb of the striker out of the area of the hook end of the safety hook for the purpose of completely opening the engine hood—the striker being swiveled along about the same angle as the lever plate—is associated with a complex design of the lever plate which, in view of the components required, leads to relatively high costs, as well. In addition, a relatively great overall height results from this design.
Because the safety hook necessary in the case of this rotary-latch closure leads to an increase in the number of components and thus to a further increase in costs, and moreover, the complete covering of the inside width of the passage cross-section of the sliding channel by the hook end of the safety hook may lead to a functioning impairment, this rotary-latch closure—by which, to be sure, the intended effects are achieved—is also at the least still high-cost.
As described in PCT Published Patent Application No. WO 03/0705 29, it is also known to achieve increased pedestrian protection in the area of the lock assembly of vehicle hoods, in that the striker is secured in a manner allowing displacement on a flange plate disposed on the vehicle hood, and at the same time, is under the force of a helical spring; however, this formation and placement of the striker requires a relatively great overall height, as well, and assuming a rotary-latch closure made up of a rotary latch, a retaining pawl and an arresting lever, is not suitable for folding the vehicle hood up into its end position after the front hood has been released by execution of a swiveling motion of the striker.
Furthermore, the closure for hoods of motor vehicles described in German Published Patent Application No. 100 54 507, which operates on the basis of a rotary latch, a retaining pawl and a striker, likewise has a relatively great overall height. This results, inter alia, from the allocation of the striker to a counter closure part which is secured in position on the engine hood and is particularly compact. It includes a striker support in which the striker is axially displaceable, and upon its axial displacement, assumes a lower or upper position as a function of the locking or release. In addition, this closure is designed in such a way that it does not operate on the basis of a catch hook.
The safety latch for vehicle covers described in German Patent No. 43 13 570 is likewise based on a swivel-mounted rotary latch as well as a swivel-mounted retaining pawl in operative connection with the rotary latch, the rotary latch cooperating with a closure bracket bent in a U-shape. This safety latch fulfills its task with regard to the locking and release of the vehicle cover, but also with regard to safety because the rotary latch has a special design and, in order to fulfill its functions, requires further components that are operatively connected to it, so that this safety latch is high-cost, as well.
According to German Published Patent Application No. 10 2005 057 820, which likewise is based on a rotary latch and a catch hook, the rotary latch is extended on its side opposite its axis, thus forming the catch hook, in such a way that the middle limb of the striker is safely receivable by the hook of the catch hook—formed in extension of the rotary latch—at its lower side in the end position of the rotary latch in execution of its swiveling motion after the rotary latch has been released by the retaining pawl, with which is associated a vertical shift of the striker into a position in which, by way of its actuation, it is ready to release the securing of the front hood and thus to open it. In this context, the lower side of the hook of the catch hook is adapted substantially to the cross-section, and therefore the shape of the middle limb of the striker in that, for example, if the cross-section of the middle limb of the striker is circular, the lower side of the hook of the catch hook is curved inwardly.
This curvature is formed in such a way that, in the end position of the catch hook in execution of its swiveling motion after the rotary latch has been released, the middle limb of the striker, in accordance with its position taken in execution of the swiveling motion of the rotary latch, is at least partially covered by the inwardly curved lower side of the hook of the catch hook in the direction of the open side of the hook, so that a secure position of the middle limb and therefore of the striker is thereby ensured before, by its actuation, the front hood is folded up into its end position. In this context, given the partial covering of the middle limb of the striker in the direction of the open side of the hook by the curved lower side of the hook of the catch hook, the lower edge of the hook, possessing a radius, is intended to lie together with the axis of the middle limb of the striker approximately on a horizontally extending axis.
Thus, the safety latch described in German Published Patent Application No. 10 2005 057 820 describes a catch hook performing the safety function, it being disposed in a manner allowing it to swivel about an axis by integrating it into the rotary latch which is disposed in a manner allowing it to swivel about its axis, so that when the retention between the rotary latch and the retaining pawl, able to swivel about the axis, is released, the swiveling motion of the catch hook corresponds to the swiveling motion of the rotary latch.